The present invention relates to a trigger-type sprayer in which a piston is reciprocated by rocking a trigger, whereby a liquid in a container is sucked up, pressurized and sprayed.
Sprayers of this type have a sprayer body which is attached to a mouth portion of a container. These conventional trigger-type sprayers are classified into two groups, three-way trigger type sprayers (FIG. 1) and two-way trigger type sprayers (FIG. 2), depending on the number of passages formed in the sprayer body.
In a three-way trigger type sprayer (hereinafter referred to as simply "three-way sprayer"), a liquid in the container flows through a vertical passage 212 via a suction tube 210 and a primary valve 211, and then flows into a slant passage 214. As a piston associated with a trigger is forced into the slant passage 214 by rocking the trigger, the liquid in the slant passage 214 is pressurized and flows into a horizontal passage 216. Then, passing through a secondary valve 217, the liquid is sprayed through an orifice of a nozzle.
In a two-way trigger type sprayer (hereinafter referred to as simply "two-way sprayer"), there is no slant passage, and the piston is disposed in the horizontal passage 216. Thus, the liquid passed through the suction tube 210 and the vertical passage 212 flows into the horizontal passage 216 via the primary valve 211. Then, the liquid is pressurized by the reciprocating piston, and is sprayed through the secondary valve 217 and the orifice.
A cylinder, which constitutes a pump mechanism in conjunction with the piston, is formed in the slant passage (in the case of three-way sprayer) or horizontal passage (in the case of two-way sprayer) of the sprayer body. The trigger is formed independently of the sprayer body, and is rockably attached thereto.
In the three-way sprayer, the direction in which the piston is pushed in is not in line with the direction of the flow of the pressurized liquid. Namely, the pressurized liquid flows into the horizontal passage from the slant passage where it is compressed, thus changing its course or flowing direction. Therefore, a component of the liquid pressure will be transmitted to the sprayer body, resulting in a liquid pressure drop. Further, the three-way sprayer of this type, which has many passages therein, is complicated in structure and relatively high in manufacturing cost, requiring a lot of components or members.
In the two-way sprayer, on the other hand, the moving direction of the piston coincides with the flowing direction of the pressurized liquid, so that no pressure drop takes place. Moreover, the two-way sprayer requires only a relatively small number of components, which leads to a reduction in manufacturing cost.
In view of the actual technological competition, however, it is necessary further to reduce the number of components used in the sprayer for lower manufacturing cost. The conventional two-way sprayer is insufficient to meet these demands.